Memory consistency and event ordering in scalable shared-memory multiprocessors
ISCA '90 Proceedings of the 17th annual international symposium on Computer Architecture
A Unified Formalization of Four Shared-Memory Models
IEEE Transactions on Parallel and Distributed Systems
Java(TM) Language Specification, The (3rd Edition) (Java (Addison-Wesley))
Java(TM) Language Specification, The (3rd Edition) (Java (Addison-Wesley))
Threads cannot be implemented as a library
Proceedings of the 2005 ACM SIGPLAN conference on Programming language design and implementation
Verification of causality requirements in Java memory model is undecidable
PPAM'09 Proceedings of the 8th international conference on Parallel processing and applied mathematics: Part II
Making the java memory model safe
ACM Transactions on Programming Languages and Systems (TOPLAS)
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The Java Memory Model (JMM) formalizes the behavior of shared memory accesses in a multithreaded Java program. Dependencies between memory accesses are acyclic, as defined by the JMM causality requirements. We study the problem of post-mortem verification of these requirements and prove that the task is NP-complete. We then argue that in some cases the task may be simplified either by considering a slightly stronger memory model or by tracing the actual execution order of Read actions in each thread. Our verification algorithm has two versions: a polynomial version, to be used when one of the aforementioned simplifications is possible, and a non-polynomial version – for short test sequences only – to be used in all other cases. Finally, we argue that the JMM causality requirements could benefit from some fine-tuning. Our examination of causality test case 6 (presented in the public discussion of the JMM) clearly shows that some useful compiler optimizations – which one would expect to be permissible – are in fact prohibited by the formal model.